Various packing or packaging machines are known for placing a product into a box, carton, or other container. However, special problems are encountered when the product to be packaged comprises stacks of discrete objects. These stacks, for example, may have previously been formed by a stacking machine and set on a support surface for further processing. Such stacks can be lifted manually and placed into a box, but if multiple stacks have to be placed in the same box, it can be difficult to maintain the integrity of the stacks as they are moved; this leads to the occasional need for a manual restacking step. Furthermore, it is difficult to lift multiple adjacent stacks of objects at the same time by hand, and therefore a person would normally be limited to lifting the stacks one at a time when placing them in a box. However, if the stacks are to be packed tightly in the box, that is, if they are to be packed with a minimal amount of space between the stacks themselves and between the stacks and the inner walls of the box, it may be difficult to manually position the stacks that are adjacent a sidewall, and especially difficult to place the last stack into a box, which stack will be bounded on four sides by box sidewalls or other stacks of products.
Stacks of products such as those discussed above can be moved by gripping the top and bottom of the stack and applying pressure to hold the stack together while it is moved. An apparatus for gripping and moving stacks in this manner is disclosed in a co-pending application entitled “Stack Transfer Device” filed concurrently herewith and assigned to the assignee of this application, the disclosure of which is hereby incorporated by reference. However, gripping a stack from the top and bottom makes it difficult to insert the stack into a previously formed box having an open top. To package a stack that is gripped in this manner, either a box must be formed around the stacks of objects while they are being gripped, or the objects must be deposited on a surface and moved again from the surface to a box.
When using a stack transfer device, such as the one disclosed in the above application, the stacks are often placed on a device called a matrix former before they are packaged. A matrix former comprises a horizontal platform and two or three upstanding, movable sidewalls forming a structure that resembles a cube with an open top and no front wall. The purpose of the matrix former is to consolidate several stacks by sliding them toward one another and removing the spaces therebetween, to make them easier to fit into a box. The upstanding walls of the matrix former, however, make it even more difficult to transfer the stacks from the matrix former to a pre-formed box or case. It would therefore be desirable to provide a method and apparatus for automatically, simultaneously, transferring a plurality of stacks of discrete objects from a support platform, such as a matrix former, to a box in a manner that preserves the integrity and arrangement of the stacks.